Method for purifying a target nucleic acid

The present invention pertains to method for purifying at least a target nucleic acid from a sample, said method comprising at least the following steps: a) incubating the sample with at least one protein-degrading compound; b) binding the target nucleic acid to a solid phase; c) eluting the target nucleic acid from the solid phase; d) incubating the eluted target nucleic acid with at least one protein-degrading compound; e) binding the target nucleic acid again to a solid phase; f) optionally eluting the bound target nucleic acid from the solid phase. It was surprisingly found that performing a second protein digestion step after the target nucleic acid was bound and eluted from a solid phase before the nucleic acids are rebound to a solid phase is very efficient in reducing remaining protein contaminations in the isolated nucleic acid.